The present invention generally relates to a cutting arrangement and more particularly, to a method of cutting a glass material by the use of a laser beam, and an apparatus for effecting said cutting method.
Referring to FIG. 5 showing a known laser cutting apparatus for a glass material, a conventional laser cutting method of a glass material and an apparatus employed therefor will be described hereinafter.
The conventional laser cutting apparatus of a glass material shown in FIG. 5 includes a laser oscillator LO for generating a laser beam LB, a reflecting mirror M for directing the laser beam LB onto a glass plate GP to be cut along a line L through a condenser lens CL, and an X-Y table TB for supporting the glass plate GP.
In the conventional arrangement as described above, the laser beam LB emitted from the laser oscillator LO is converged onto the glass substrate GP by the condenser lens CL, and the glass substrate GP is simultaneously moved by the X-Y table TB. In the case where a carbonic acid gas laser is employed for the laser oscillator LO, since the glass material has a high absorption rate with respect to the wavelength 10.6 .mu.m of said laser beam, the portion of the glass substrate GP subjected to the irradiation of the laser beam LB is fused to be cut. Meanwhile, when a YAG laser is employed for the laser oscillator LO, although the absorption rate of the glass material with respect to the wavelength 1.06 .mu.m of said laser beam is generally low, it is reported by Kurobe et al. that soda-lime glass may be cut off (according to a collection of papers at the scientific lecture meeting for the spring general conference of Precision Engineering Association, 1988, page 853).
However, in the conventional glass cutting method employing a carbonic acid gas laser as described above, the glass material absorbs the laser beam so as to be fused and cut by heating. Therefore, since a predetermined cutting width is required, with sagging or run of the glass material, or a portion affected by heat being produced around the cut portion, sufficient processing accuracy can not be achieved. Another problem with this process is that a crack may occur in the vicinity of the cut portion due to remaining thermal stress.
Meanwhile, in the practice which employs the YAG laser, due to the fact that the laser absorption rate of glass is generally low, energy efficiency is undesirably deteriorated, with glass materials which can be cut being limited. Furthermore, in the case where another layer, such as a vapor deposition layer, is present on the reverse surface of the glass material, as in a glass substrate for liquid crystal, such vapor deposition layer may be undesirably processed by the laser beam transmitted through the glass substrate.